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High Speed (MHz) Switch Mode Power Supplies (SMPS) using Coreless PCB Transformer Technology
Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media. (Power Electronics)ORCID iD: 0000-0001-5326-2563
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The most essential unit required for all the electronic devices is the Power Supply Unit (PSU). The main objective of power supply designers is to reduce the size, cost and weight, and to increase the power density of the converter. There is also a requirement to have a lower loss in the circuit and hence in the improvement of energy efficiency of the converter circuit. Operating the converter circuits at higher switching frequencies reduces the size of the passive components such as transformers, inductors, and capacitors, which results in a compact size, weight, and increased power density of the converter. At present the switching frequency of the converter circuit is limited due to the increased switching losses in the existing semiconductor devices and in the magnetic area, because of increased hysteresis and eddy current loss in the core based transformer. Based on continuous efforts to improve the new semi conductor materials such as GaN/SiC and with recently developed high frequency multi-layered coreless PCB step down power transformers, it is now feasible to design ultra-low profile, high power density isolated DC/DC and AC/DC power converters. This thesis is focussed on the design, analysis and evaluation of the converters operating in the MHz frequency region with the latest semi conductor devices and multi-layered coreless PCB step-down power and signal transformers.

An isolated flyback DC-DC converter operated in the MHz frequency with multi-layered coreless PCB step down 2:1 power transformer has been designed and evaluated. Soft switching techniques have been incorporated in order to reduce the switching loss of the circuit. The flyback converter has been successfully tested up to a power level of 10W, in the switching frequency range of 2.7-4 MHz. The energy efficiency of the quasi resonant flyback converter was found to be in the range of 72-84% under zero voltage switching conditions (ZVS). The output voltage of the converter was regulated by implementing the constant off-time frequency modulation technique.

Because of the theoretical limitations of the Si material MOSFETs, new materials such as GaN and SiC are being introduced into the market and these are showing promising results in the converter circuits as described in this thesis. Comparative parameters of the semi conductor materials such as the

vi

energy band gap, field strengths and figure of merit have been discussed. In this case, the comparison of an existing Si MOSFET with that of a GaN MOSFET has been evaluated using a multi-layered coreless PCB step-down power transformer for the given input/output specifications of the flyback converter circuit. It has been determined that the energy efficiency of the 45 to 15V regulated converter using GaN was improved by 8-10% compared to the converter using the Si MOSFET due to the gate drive power consumption, lower conduction losses and improved rise/fall times of the switch.

For some of the AC/DC and DC/DC applications such as laptop adapters, set-top-box, and telecom applications, high voltage power MOSFETs used in converter circuits possess higher gate charges as compared to that of the low voltage rating MOSFETs. In addition, by operating them at higher switching frequencies, the gate drive power consumption, which is a function of frequency, increases. The switching speeds are also reduced due to the increased capacitance. In order to minimize this gate drive power consumption and to increase the frequency of the converter, a cascode flyback converter was built up using a multi-layered coreless PCB transformer and this was then evaluated. Both simulation and experimental results have shown that with the assistance of the cascode flyback converter the switching speeds of the converter were increased including the significant improvement in the energy efficiency compared to that of the single switch flyback converter.

In order to further maximize the utilization of the transformer, to reduce the voltage stress on MOSFETs and to obtain the maximum power density from the power converter, double ended topologies were chosen. For this purpose, a gate drive circuitry utilising the multi-layered coreless PCB gate drive transformer was designed and evaluated in both a Half-bridge and a Series resonant converter. It was found that the gate drive power consumption using this transformer was less than 0.8W for the frequency range of 1.5-3.5MHz. In addition, by using this gate drive circuitry, the maximum energy efficiency of the series resonant converter was found to be 86.5% with an output power of 36.5W.

Place, publisher, year, edition, pages
Sundsvall, Sweden: Mid Sweden University , 2011. , 104 p.
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 62
Keyword [en]
SMPS, High Frequency converters, Coreless PCB transformers
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:miun:diva-13964Local ID: STCISBN: 978-91-86694-41-8OAI: oai:DiVA.org:miun-13964DiVA: diva2:422578
Presentation
2011-05-27, M102, Mid Sweden University, Holmgatan 10, Sundsvall, 10:15 (English)
Opponent
Supervisors
Funder
EU, European Research Council
Available from: 2011-06-13 Created: 2011-06-13 Last updated: 2016-10-19Bibliographically approved
List of papers
1. A ZVS Flyback DC-DC Converter using Multilayered Coreless Printed Circuit Board (PCB) Step Down Power Transformer
Open this publication in new window or tab >>A ZVS Flyback DC-DC Converter using Multilayered Coreless Printed Circuit Board (PCB) Step Down Power Transformer
2010 (English)In: World Academy of Science, Engineering and technology, Paris: World Academy of Science,Engineering and Technology , 2010, 148-155 p.Conference paper (Refereed)
Abstract [en]

The experimental and theoretical results of a ZVS (Zero Voltage Switching) isolated flyback DC-DC converter using multilayered coreless PCB step down 2:1 transformer are presented.The performance characteristics of the transformer are shown which are useful for the parameters extraction. The measured energy efficiency of the transformer is found to be more than 94% with the sinusoidal input voltage xcitation. The designed flyback converter has been tested successfully upto the output power level of 10W,with a switching frequency in the range of 2.7MHz-4.3MHz. The input voltage of the converter is varied from 25V-40V DC.Frequency modulation technique is employed by maintaining constant off time to regulate the output voltage of the converter. The energy efficiency of the isolated flyback Converter circuit under ZVS condition in the MHz frequency region is found to be approximately in the range of 72-84%. This paper gives the comparative results in terms of the energy efficiency of the hard switched and soft switched flyback Converter in the MHz frequency region.

Place, publisher, year, edition, pages
Paris: World Academy of Science,Engineering and Technology, 2010
Series
, World Academy of Science ,Engineering and Technology,ISSUE 70,OCTOBER 2010, ISSN 1307-6892 ; 70
Keyword
Coreless PCB step down transformer, DC-DC Converter, Flyback, Hard Switched Converter, MHz Frequency region, Multilayered PCB transformer, Zero Voltage Switching
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-12278 (URN)2-s2.0-80052088161 (ScopusID)
Conference
International Conference on Electrical Machines and Power Electronics (ICEMPE),2010
Available from: 2010-11-24 Created: 2010-11-24 Last updated: 2016-09-26Bibliographically approved
2. Comparative Results of GaN and Si MOSFET in a ZVS Flyback Converter using Multilayered Coreless Printed Circuit Board Step-Down Transformer
Open this publication in new window or tab >>Comparative Results of GaN and Si MOSFET in a ZVS Flyback Converter using Multilayered Coreless Printed Circuit Board Step-Down Transformer
2010 (English)In: Proceedings of 2010 3rd International Conference on Power Electronics and Intelligent Transportation System, Shenzhen: IEEE conference proceedings, 2010, 318-321 p.Conference paper (Refereed)
Abstract [en]

The aim of this paper is to compare two different material MOSFETs performance namely GaN (Gallium Nitride) and conventional Si (Silicon) in Zero Voltage Switching (ZVS) flyback converter circuit with Coreless PCB step down transformers. The switching frequency of the regulated converter is in the range of 3.2-5MHz. In high frequency circuits, proper selection of MOSFETs is required in order to have low gate drive power consumption so that high energy efficiency of the converter can be achieved. Even though Si MOSFET has already known for its popularity in low to medium power converters and high frequency applications, GaN MOSFET device could produce better results.  This can be done by reducing the total switching loss, conduction loss because of its low Rds-on and gate drive power consumption of the converter as a result of low gate charge, Qg. From the experimental results, it can be observed that GaN MOSFET can produce higher energy savings including gate drive power by gaining approximately 8%-10% efficiency compared to its counterpart, Si MOSFET in a regulated 45-15V isolated DC-DC converter.

Place, publisher, year, edition, pages
Shenzhen: IEEE conference proceedings, 2010
Keyword
Coreless Printed Circuit Board (PCB) step down power transformer, DC-DC Converter, GaN MOSFET, MHz frequency region, ZVS flyback converter.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-14644 (URN)000306295600014 ()978-1-4244-9162-9/10 (ISBN)
Conference
2010 3rd International Conference on Power Electronics and Intelligent Transportation System
Available from: 2011-10-27 Created: 2011-10-27 Last updated: 2014-08-31Bibliographically approved
3. High Speed Cascode Flyback Converter Using Multilayered Coreless Printed Circuit Board (PCB) Step-Down Power Transformer
Open this publication in new window or tab >>High Speed Cascode Flyback Converter Using Multilayered Coreless Printed Circuit Board (PCB) Step-Down Power Transformer
2011 (English)In: Proceedings of 8th International Conference on Power Electronics-ECCE Asia, IEEE conference proceedings, 2011, 1856-1862 p.Conference paper (Refereed)
Abstract [en]

In this paper, design and analysis of the high speed isolated cascode flyback converter using multilayered coreless PCB step down power transformer is presented. The converter is tested for the input voltage variation of 60-120V with a nominal DC input voltage of 90V. The designed converter was simulated and tested successfully up to the output power level of 30W within the switching frequency range of 2.6-3.7MHz. The cascode flyback converter is compared with the single switch flyback converter in terms of operating frequency, gate drive power consumption, conduction losses and stresses on MOSFETs. The maximum energy efficiency of the cascode converter is approximately 81% with a significant improvement of about 3-4% compared to single switch flyback converter. The gate drive power consumption which is more dominant compared to conduction losses of the cascode converter using GaN MOSFET is found to be negligible compared to single switch flyback converter.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2011
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-13248 (URN)10.1109/ICPE.2011.5944386 (DOI)STC (Local ID)978-1-61284-956-0 (ISBN)978-1-61284-958-4 (ISBN)STC (Archive number)STC (OAI)
Projects
High Speed Switch Mode Power Supplies
Available from: 2011-02-11 Created: 2011-02-11 Last updated: 2016-10-19Bibliographically approved
4. Coreless Printed Circuit Board (PCB) StepdownTransformers for DC-DC ConverterApplications
Open this publication in new window or tab >>Coreless Printed Circuit Board (PCB) StepdownTransformers for DC-DC ConverterApplications
2010 (English)In: PROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, ISSUE 70, OCTOBER 2010, ISSN:1307-6892, France: World Academy of Science Engineering and Technology , 2010, 380-389 p.Conference paper (Refereed)
Abstract [en]

In this paper, multilayered coreless printed circuit board (PCB) step-down power transformers for DC-DC converter applications have been designed, manufactured and evaluated. A set of two different circular spiral step-down transformers were fabricated in the four layered PCB. These transformers have been modelled with the assistance of high frequency equivalent circuit and characterized with both sinusoidal and square wave excitation. This paper provides the comparative results of these two different transformers in te rms of their resistances, self, leakage, mutual inductances, coupling coefficient and also their energy efficiencies. The operating regions for optimal performance of these transformers for power transfer applications are determined. These transformers were tested for the output power levels of about 30 Watts within the input voltage range of 12-50 Vrms. The energy efficiency for these step down transformers is observed to be in the range of 90%-97% in MHz frequency region.

Place, publisher, year, edition, pages
France: World Academy of Science Engineering and Technology, 2010
Series
, WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, ISSN 1307-6892 ; 70
Keyword
Coreless Step down Transformer, DC-DC Converter applications, High frequency transformer, MHz operating frequency, Multilayered PCB transformers, Power Transfer Applications
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-12242 (URN)2-s2.0-84871422637 (ScopusID)
Conference
International Conference on Electrical Machines and Power Electronics
Available from: 2010-11-17 Created: 2010-11-17 Last updated: 2016-09-22Bibliographically approved
5. Radiated Emissions of Multilayered Coreless Printed Circuit Board Step-Down Power Transformers in Switch Mode Power Supplies
Open this publication in new window or tab >>Radiated Emissions of Multilayered Coreless Printed Circuit Board Step-Down Power Transformers in Switch Mode Power Supplies
2011 (English)In: 8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia 2011, IEEE conference proceedings, 2011, 960-965 p.Conference paper (Refereed)
Abstract [en]

This paper addressesradiatedEMI issues in Coreless PCB step-down transformers used for power transfer applications. In case of SMPS circuits, since the waveforms are not sinusoidal in nature, most of theradiatedemissionsare not only from fundamental frequency component but also from harmonic contents. According to antenna theory,radiatedEMI for three different power transformers of different radii were estimated for fundamental frequency of 2MHz to 300MHz. The computations were made for both sinusoidal and square wave excitations and at a load power of 20W. The calculatedradiatedpower obtained for simulated waveforms and for practical measured current waveforms are in good agreement with each other up to certain bandwidth. These computational results confirm thatradiatedpower can be reduced in three layered 2:1 transformer compared to two layered 2:1 transformer. Also theradiatedemissionsare negligible in case of sinusoidal excitations compared to square wave excitations. © 2011 IEEE.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2011
Keyword
Harmonics; MHz frequency of operation; Multilayered Coreless PCB step down power transformers; Radiated EMI
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-13247 (URN)10.1109/ICPE.2011.5944654 (DOI)2-s2.0-80052087677 (ScopusID)STC (Local ID)978-1-61284-956-0 (ISBN)978-1-61284-958-4 (ISBN)STC (Archive number)STC (OAI)
Conference
8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia;Jeju;30 May 2011through3 June 2011;Category numberCFP11CPB-USB;Code86200
Available from: 2011-02-11 Created: 2011-02-11 Last updated: 2016-10-19Bibliographically approved

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